PURPOSE: We assessed the usefulness of color Doppler imaging and spectral analysis in monitoring the effect of isovolemic hemodilution on retinal vein occlusion. METHODS: Color Doppler imaging was used to measure the systolic and diastolic blood flow velocities and the resistance index (RI) in the central retinal artery and the maximum and minimum blood flow velocities in the central retinal vein of affected eyes and contralateral unaffected eyes before and 1 day after isovolemic hemodilution in 70 adults (40 men and 30 women; mean age, 62.4 +/- 13.7 years) who presented with retinal vein occlusion. RESULTS: With hemodilution, the hematocrit value was decreased from 41.8 +/- 3.0 to 33.0 +/- 3.0. In central retinal vein occlusion, the pretreatment arterial and venous flow velocities of affected eyes were significantly lower than those of unaffected eyes. After hemodilution in eyes affected by ischemic occlusion, a significant improvement in the RI in the central retinal artery was observed without changes in venous flow velocity. After hemodilution in eyes affected by non-ischemic occlusion, a significant increase in maximal venous flow velocity only was noted. In branch retinal vein occlusion, no significant difference was observed in the RI between affected and unaffected eyes. After hemodilution, an improvement in RI was noted only for affected eyes. CONCLUSIONS: The present results confirm the potential value of Doppler analysis in monitoring the impact of hemodilution on arterial and venous velocity in patients with central retinal vein occlusion.

Adult↗

PubMedDate not supplied

Doppler study of fasting and postprandial resistance indices in the superior mesenteric artery in healthy subjects and patients with cirrhosis.

PURPOSE: We assessed the resistance index (RI) in the superior mesenteric artery under fasting and postprandial conditions in healthy subjects and in patients with cirrhosis to determine whether the amount of change in the RI reflects the presence or severity of liver dysfunction. METHODS: Fifteen subjects with normal livers and 27 patients with cirrhosis underwent Doppler sonography of the superior mesenteric artery before and after ingesting a standard meal. The RI at baseline (fasting state) and the postprandial RI were compared between the 2 groups. The fasting RIs and post postprandial RIs changes in cirrhotic patients were correlated with the severity of disease. RESULTS: No difference was found between the baseline RIs in healthy (RI = 0.85) and cirrhotic subjects (RI = 0.84), nor was there a difference in baseline RIs between subgroups of cirrhotic patients according to the severity of liver disease. The RI decreased significantly (p < 0.05) after the meal in both the healthy (13%) and cirrhotic (8%) subjects, but the postprandial decrease was significantly less pronounced (p < 0.05) in cirrhotic patients than in healthy subjects. Among cirrhotic patients, there was no correlation between the postprandial decrease of the RI and severity of liver disease. CONCLUSIONS: The marked decrease in the postprandial RI in the SMA in healthy subjects is generally not seen in patients with cirrhosis, and changes in the postprandial RI do not reliably predict the severity of liver dysfunction.

Adult↗

PubMedDate not supplied

Diffusion imaging with a multi-echo MISSTEC sequence.

An imaging method is presented to measure the water-diffusion coefficient. The sequence (MISSTEC) uses the simultaneous acquisition of a spin echo and several stimulated echoes with the same intensity except for diffusion weighting. The optimal number of stimulated echoes was calculated to minimize the diffusion coefficient error (D). D values obtained in vitro and in vivo were in good agreement with those from the spin-echo sequence (IntraVoxel Incoherent Motion [IVIM] method). The total acquisition time is half that of the classic IVIM method.

Brain↗

PubMedDate not supplied

[Radioisotopes, ultrasonics and thermography in the diagnosis of cerebral circulatory disorders].

Explore the source record for details and available documents.

Carotid Artery Thrombosis↗

PubMedDate not supplied

[Ultrasonographic study of the cerebral circulation in elderly subjects (author's transl)].

The amount of diastolic blood flow in the carotid and vertebral axes determines the tolerance capacity of the cerebral circulation to physiological variations. In the elderly subject this "circulatory reserve" is modified by increases in cerebral circulation resistance, but also by various common cardiac or blood pressure disorders. Furthermore, direct visualization of the atheromatous plaques and calcifications in the vessel walls by ultrasonography can reveal lesions that have no clinical expression.

Aged↗

PubMedDate not supplied

Effects of indomethacin on cerebral hemodynamics at rest and during endotracheal suctioning in preterm neonates.

The effect of therapeutic doses of indomethacin versus placebo (saline) on cerebral hemodynamics was studied in nine mechanically ventilated preterm infants. Recordings were made at rest and during endotracheal suctioning. Indomethacin at a dose of 0.2 mg/kg body weight was infused over 5 min. Compared to placebo, there was a significant decrease in Doppler mean frequency in the anterior cerebral artery within minutes of starting the indomethacin infusion during the resting period after the first (p less than 0.01), second (p less than 0.001) and third (p less than 0.025) doses. This effect has persisted during endotracheal suctioning. Thus, indomethacin alters cerebral hemodynamics by decreasing Doppler mean frequency. In view of these findings, and particularly because of the alteration in the resting cerebral hemodynamics, the recommendation of prophylactic treatment with indomethacin remains questionable.

Blood Flow Velocity↗

PubMedDate not supplied

Cardiac cycle-dependent alternating flow in vertebral arteries with subclavian artery stenoses.

Continuous-wave Doppler sonography is a reliable method for detecting severe subclavian stenosis and occlusion as well as subclavian steal. Intermediate stages leading to subclavian steal can also be detected. These are characterized by a cardiac-phase-dependent alternating flow direction in the vertebral artery. Some cases of proximal subclavian or proximal vertebral artery stenosis produce a systolic deceleration of flow in the vertebral artery. Stenosis and occlusion of the subclavian artery as well as stenosis of the subclavian and vertebral arteries can be distinguished. The pulse curve changes described can be reversed by a vascular by-pass. Alternating flow direction or systolic deceleration of flow in the radial artery could also be observed or induced in a iatrogenic model using Cimino's a-v fistula in the arm in patients on dialysis. The results in beginning subclavian steal situations can be applied in principle to other collateral circulations, and in particular to the hemodynamics in the region of watersheds.

Arterial Occlusive Diseases↗

PubMedDate not supplied

Ultrasound characterization and quantification of carotid atherosclerosis lesions.

The development of ultrasonography in vascular applications has entailed research of ultrasound parameters leading to precise the diagnosis and quantification of carotid lesions in routine. The use of recent colour Doppler imaging techniques (velocity or power encoding) is recommended as they allow a better definition of the lesions and recesses. At present, features of plaque that could be related to increased incidence of stroke are: echogenicity, with a more frequent observation of anechoic or hypoechoic lesions in the case of clinical signs; texture, with frequent haemorrhage; surface contour, with a high rate of ulcerations which were accompanied by stroke; plaque motion, with a significant alteration in plaque motility in symptomatic patients; progression or regression in size, with a faster progression of anechoic and hypoechoic plaques; an increase in plaque volume is associated with a greater risk of stroke; a significant relationship between the presence of "ulcers" and embolic activity. The quantification of stenosis degree could be made using velocity criteria and/or morphological criteria. Velocity criteria could be obtained at the site of the stenosis (direct criteria) or downstream the carotid stenosis using Duplex systems. Morphological criteria could be obtained using B-mode imaging or colour Doppler but this quantification remains difficult in case of diffuse carotid stenoses or very severe stenoses.

Arteriosclerosis↗